How does fsi affect an engine?
A spark ignition engine is a type of internal combustion engine that can be used in trucks, automobiles, portable and stationary equipment.The working fluids and fuel vapors entering the cylinder are referred to as "stratified charge".Usually the fuel is injected into the cylinder or enters as a fuel rich Vapor where a spark or other means are used to start the engine.Higher compression ratios without "knock" and leaner air/fuel ratio can be achieved with a stratified charge.
A four-stroke Otto cycle engine is powered by a mixture of air and fuel during the intake stroke.A homogeneous charge is created when a mixture of air and fuel is ignited by a spark plug near the top of the compression stroke.
The air/fuel ratio is kept very close to stoichiometric, meaning it contains the exact amount of air necessary for complete combustion of the fuel.This gives stable combustion, but it places an upper limit on the engine's efficiency: any attempt to improve fuel economy by running a much leaner mixture (less fuel or more air) with a homogeneous charge results in slower combustion and a higher engine temperature.
A higher mechanical compression ratio can be used to improve efficiency.There is no risk of pre-ignition or engine knock because fuel is not injected until just before the start of the engine.
The engine can run on a leaner air/fuel ratio using a method called stratified charge, in which a small charge of a rich fuel mixture is ignited first and used to improve the efficiency of the engine.
If a lean mixture is present at the spark plug, it can be problematic.Fueling a petrol engine directly allows more fuel to be directed towards the spark-plug.A stratified charge is when the air/fuel ratio is not homogeneity throughout the combustion-chamber, but varies in a controlled way across the volume of the cylinder.
Where there is no 'in cylinder' stratification, the inlet mixture can be so lean that it is unable to be ignited by a conventional spark plug.In the case of a petrol engine that is fed into a small combustion chamber next to the main lean-mixture chamber, a conventional mixture strength of 12-15:1 can be used to ignite this extremely lean mixture.The charge can be combusted by the large flame front from this burning mixture.The lean charge is 'burnt' and the engine that uses this method is no longer subject to knock or uncontrollable combustion.The fuel being burnt in the lean charge is not restricted.The specific energy output is dependent on the calorific value of the fuel.
A relatively rich air/fuel mixture is directed to the spark-plug.A strong, even and predictable flame-front is given by this mixture.This results in a high-quality fire in the cylinder.
It is important to compare contemporary directly fueled petrol engines with direct-injection diesel engines.Higher engine speeds and greater power for sporting engines can be achieved by using petrol instead of diesel.Diesel fuel has a higher energy density, and in combination with higher combustion pressures can deliver very strong torque and high efficiency for more "normal" road vehicles.
The comparison of burn rates is simplistic.The two types of engines operate on completely different principles.The external characteristics were obvious in earlier manufactured editions.Diesel only sucked in air and the fuel was directly injected into the cylinder in most petrol engines.The spark plug starts to ignite the mixture in the cylinder at up to forty degrees before the top dead centre of the engine.The maximum pressure is reached just after the top dead centre, with the pressure diminishing as the piston travels down the bore.I.e.The cylinder volume in relation to the cylinder pressure-time generation is essentially constant.Diesel engine operation only uses the motion of the piston to move to the top dead centre to breathe and compress air.The maximum cylinder pressure has been reached.The fuel is injected into the cylinder and the expansion is started by the high temperature of the compressed air.As the fuel burns, it exerts pressure on the piston, which in turn develops Torque at the crankshaft.The diesel engine is running at a constant pressure.The cylinder is moving as the gas expands.Over a longer time interval, the crank experiences a greater Torque than the petrol equivalent.
The principle of injecting fuel directly into the combustion chamber was first invented by George Brayton in 1887, but it has been used to good effect in petrol engines for a long time.Brayton describes his invention as follows: "I have discovered that heavy oils can be mechanically converted into a finely-divided condition within a firing portion of the cylinder or in a communicating firing chamber.""I have for the first time, so far as my knowledge extends, regulated speed by variably controlling the direct discharge of liquid fuel into the combustion chamber or cylinder into a finely-divided condition highly favorable to immediate combustion", reads another part.The first engine to use a lean burn system was this one.The quantity of fuel injected was the sole factor controlling the output and speed of the engine.
The idea of a lean burn "stratified charge" engine was started by Harry Ricardo.He made improvements to his designs in the 1920s.
The first example of gasoline direct injection was a Swedish engineer's engine.When using the ultra lean burn principle, the engines would inject the fuel in the end of the compression stroke, ignite it with a spark plug, and then switch over to run on gasoline or diesel.The multi fuel system developed by Texaco was very similar to the design of the Hesselman design.The TCCS was found to have an increase in economy of more than 30%.
Honda's CVCC engine, which was released in the early 1970s models of Civic, Accord and City, had wide market acceptance for a long time.The CVCC system had conventional inlet and exhaust valves and a third, supplementary, inlet valve that charged an area around the spark plug.A metal plate isolated the spark plug and CVCC inlet from the main cylinder.A series of flame fronts shot into the main charge through the perforations.The high power-to-weight ratio was achieved by the engines in the Honda City.
The Jaguar V12 engine was developed in the 1980s.In order to reduce the engine's very heavy fuel consumption, the May Fireball design was used in the High Efficiency version.
Air was admitted through the transfer port and a rich fuel mixture was injected into the cylinder just before the scooter was to start.The injection system used a timed pumping cylinder and a non-return valve.
The charge is squirted into the cylinder when the rising pressure raises a poppet valve off its seat.It is aimed at the spark plug area.The poppet valve is immediately shut down by the combustion pressure and the flame front ignites the lean mixture areas in the cylinder.[4]
Volkswagen uses a variety of gasoline engines, including its direct injection 1.2, 1.4, 1.5, 1.8 and 2.0 litres TFSI engines.